Hydrocarbon Formation from Syngas with In-Operando Monitoring of Cobalt- and Manganese-Based (pre)Catalysts Using X-ray Diffraction.

Two-layered metal oxides (LiCoO and cobalt-doped K MnO, < 1) were explored as precatalysts for nanoconfined cobalt-based Fischer-Tropsch catalysts for conversion of syngas (CO and H) to hydrocarbons. Ex situ, in situ, and PDF XRD analyses are presented. Based on in situ XRD analysis, LiCoO underwent reduction to predominantly cubic and hexagonal phases of cobalt metal. Reaction with syngas resulted in the generation of carbon, cobalt carbide, and lithium carbonate, in addition to the metallic cobalt phases. In the case of cobalt-doped birnessite, catalyst activation converted the birnessite phase to manganite and the cobalt to elemental cobalt, along with similar lithium and carbon phases. Conversion of syngas to C through C products was observed. The best conversions were observed for the LiCoO precursor catalyst, with generally a low olefin-to-paraffin ratio. While the conversions for the cobalt-doped birnessite precatalyst were generally lower, with lower chain lengths (up to C), these catalysts gave a strikingly high olefin-to-paraffin ratio: in the best case, greater than 20:1.